Ethylene Control of Anthocyanin Synthesis in Sorghum

Abstract

The influence of light on ethylene production in the sorghum tissue was determined on 10-mm sections of tissue like those used for anthocyanin analysis. The sections were cut from dark-grown tissue under a safelight filter made of green Rohm and Haas acrylic that produced no detectable effect on anthocyanin synthesis in seedlings even after prolonged exposure. After cutting, sections were left on moist filter paper for 6 hr for dissipation of wound ethylene. The sections of tissue were then sealed in 1 0-ml Erlenmyer flasks containing 2 ml of sterile 1.5% agar solution with rubber vaccine caps. Light treatment was the same as for the other experiments. Ethylene concentration in the flask was measured by injecting a 1-ml sample of gas from the flask into a gas chromatograph equipped with a flame ionization attachment. Oven temperature was 150 C, and nitrogen flowed at 60 ml/min through a 6-mm outer diameter, 150-cm activated alumina column. Identity of the gas was established by cochromatography with standards.Calculation of Rate of Synthesis. The rate of anthocyanin synthesis at different times for plants receiving no ethylene treatment was taken from data in Figure 1 and is the slope of the curve at 2-hr increments. The rate of anthocyanin synthesis at different times in the presence of ethylene was taken from data in Figures 1 and 3. It was assumed that anthocyanin followed the normal ethylene-free synthesis pattern until ethylene was added and that the slope of the line connecting this point with the measured amount of anthocyanin present at the end of 24 hr was representative of the rate of synthesis under ethylene at the time ethylene was added. The rate of anthocyanin synthesis at different times for plants receiving ethylene initially but with subsequent removal was taken from data in Figure 4. It was assumed that anthocyanin synthesis under ethylene followed a straight line connecting the initial amount of anthocyanin with the measured amount of anthocyanin after 24-hr treatment with ethylene. Synthesis would follow this line until ethylene was removed, and the line connecting this point with the measured amount of anthocyanin in the tissue at 24 hr would be representative of the rate of synthesis at the time ethylene was removed.Unless otherwise stated, all experiments were repeated a minimum of three times with three replicates for each treatment. RESULTSNormal light-stimulated synthesis of anthocyanin in sorghum seedlings showed an initial lag phase of 8 hr after the darkgrown seedlings were placed in the light (Fig. 1). Rapid formation of anthocyanin began at the end of the lag phase and continued linearly throughout the time in which these experiments were conducted.

Involvement of Ethylene in Phytochrome-mediated Carotenoid Synthesis

“…Ethylene prevents development of geotropic curvature by inhibiting lateral auxin transport (4), whereas geotropic reactivity is increased by red light in mustard seedlings (23). Brief illumination with red light induces anthocyanin synthesis in etiolated mustard seedlings (20. OF CAROTENOGENESIS 633 21), whereas we find that in this tissue ethylene inhibits accumulation of anthocyanin when applied continually, just as it does if applied when anthocyanin accumulation is occurring (11). Thus in several cases a red light-induced reduction in the rate of ethylene biosynthesis may mediate the response to the phytochrome system.…”

Light-induced Ethylene Production in Sorghum

“…E55 and E57 were used. The seedlings were grown in the dark on agar in 125-ml Erlenmeyer flasks at 28 + 1 C as previously described (5 measurements of ethylene production, 10-mm sections were cut just proximal to the first node from the seedling tissue under a green safelight (fluorescent lamp with acrylic and cellophane filters) (3) that produced no detectable effect on ethylene production even after extended, continuous exposure.…”

“…E55 and E57 were used. The seedlings were grown in the dark on agar in 125-ml Erlenmeyer flasks at 28 + 1 C as previously described (5 measurements of ethylene production, 10-mm sections were cut just proximal to the first node from the seedling tissue under a green safelight (fluorescent lamp with acrylic and cellophane filters) (3) that produced no detectable effect on ethylene production even after extended, continuous exposure.After cutting, the sections were left on moist paper for 4 hr for dissipation of wound ethylene. The sections of tissue were then mixed, and a random selection of 10 sections for each sample was sealed with a rubber vaccine cap in a 20-ml vaccine bottle containing 2 ml of sterile 1.5% agar along one side.…”

“…E55 and E57 were used. The seedlings were grown in the dark on agar in 125-ml Erlenmeyer flasks at 28 + 1 C as previously described (5 After cutting, the sections were left on moist paper for 4 hr for dissipation of wound ethylene. The sections of tissue were then mixed, and a random selection of 10 sections for each sample was sealed with a rubber vaccine cap in a 20-ml vaccine bottle containing 2 ml of sterile 1.5% agar along one side.…”

Effects of α-aminooxyacetic acid on the level of polyamines, anthocyanins and photosynthetic pigments in seedlings of common buckwheat (Fagopyrum esculentum Moench)

“…Ethylene has been shown to influence the biosynthesis of light-induced anthocyanin formation in plants (Craker et al 1971;Cracker and Wetherbee 1973). In the case of sorghum tissue the rate of anthocyanin formation was dependent upon the time of ethylene treatment in relation to light exposure and the stage of the anthocyanins production (Craker et al 1971).…”